Implicit Differentiation
If:
$$F(x,y)=0$$
then differentiating with respect to $$x$$ gives:
$$\frac{\partial F}{\partial x}+\frac{\partial F}{\partial y}\frac{dy}{dx}=0$$
Hence:
$$\frac{dy}{dx}=-\frac{F_x}{F_y}$$
provided:
$$F_y\neq0$$
Usage
- Used when $$y$$ is not explicitly expressed as a function of $$x$$.